[Leetcode] (python): 031-next permutation

Source of the topic

https://leetcode.com/problems/next-permutation/

Implement next permutation, which rearranges numbers into the lexicographically next greater permutation of numbers.

If Such arrangement is not a possible, it must rearrange it as the lowest possible order (ie, sorted in ascending order).

The replacement must is in-place, do not allocate extra memory.

Test instructions Analysis

Input: An array

Output: An array (in-situ operation)

Conditions: The output array is the next larger array than the input array. such as [1, 2, 3] = = [1, 3, 2]

If the input is the largest, then the output is the smallest array. such as [3, 2, 1] = = [1, 2, 3]

Topic ideas

1. From the back forward to find the first larger than the previous number, if not, it is already the largest array, directly in the ascending sort (List.sort ()) return
2. If you find the maximum value, record its position index, and then find a minimum value that is larger than nums[index-1] after index (including index) and swap it with nums[index-1]
3. Bubbles sort the nums array elements after index (including index)

AC Code (PYTHON)

1_author_ ="YE"2 #-*-coding:utf-8-*-3 classsolution (object):4     defnextpermutation (Self, nums):5         """6 : Type Nums:list[int]7 : Rtype:void does not return anything, modify Nums in-place instead.8         """9         #print (nums)TenLen1 =Len (nums) Oneindex =-1 A          forIinchRange (len1-1): -             ifNums[len1-1-i] > nums[len1-i-2]: -index = len1-1-I the                  Break -         ifindex = =-1: - Nums.sort () -         Else: +Minindex =Index -MinValue =Nums[index] +              forIinchRange (len1-index-1): A                 ifMinValue > Nums[index + i + 1] > Nums[index-1]: atMinindex = index + i + 1 -MinValue =Nums[minindex] -  -Nums[minindex] = nums[index-1] -NUMS[INDEX-1] =MinValue -  in             #sort other numbers from index -Numbers = Len1-Index to             #print (Numbers) +              forIinchRange (numbers-1): -                 Print('I:', i) the                  forJinchRange (Numbers-i-1): *                     ifNUMS[LEN1-J-1] < nums[len1-j-2]: $temp = nums[len1-j-1]Panax NotoginsengNums[len1-j-1] = nums[len1-j-2] -Nums[len1-j-2] =Temp the  +             #print (Minindex, minvalue) A         #print (nums)

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[Leetcode] (python): 031-next permutation